Isomerization of normally liquid paraffins



, erization of straight chain parafiin hydrocarbons isomers increases more than arithmeticaily so which are normally liquid. that in cases of isomerization involving turee to hydrocarbon mixtures containing these comis not possible by analytical methods but c he parafiin hydrocarbons such as. n-pentane or 20 ides to efiect isomeflzatlon of the normally liq- .are more reactive and. in the case of gasoline treating hydrocarbon fractions boilingwithin the ture and properties of normal parafin hydrocar- 35 position and other side reactions occur simulta- Raiente J raises i t I 2 3i aeoann rsorornrzn'rron or Noni rams: mo

sens

dristid V. Grosse, Bronxyille, N. 222, and Herman Pines, Riverside, m, esslenor to Unit; e? on Products @ompany, Chicago, or, a oornoration of Delaware g. Application May 25, wet,

Serial No; d8$$38 This application is a continuation-impart of ures are not available for the neo-pentane. our co=pending application Serial #282,083 filed ilarly, the isomeric hexanes, heptanes, and co- June 30, 1939, now Patent No. 2,336,862, which is tanes will show the same progressive relationships a continuation-impart of application Serial as their structure becomes more condensed. As #118,587 filed December 31, 1936. 5 the molecular weight of peramn hydrocarbons This invention relates particularly to the isomincreases, the number of possible and known In a more specific sense, the invention is appli-v of n-paramns and particularly n para in adcable notonly to individual paramn hydrocar- 1o mixture with other hydrocarbons in oasolines, bons of normal straishtchain structure but also the determination of the extent of isomerleation pounds in substantial percentages such as estimated from the observed change in antistraight run gasolines and their fractions-which knock value.

contain in addition to parafiin hydrocarbons of 15 In one spe ifi em n p n -V 11- his'hly knocking characteristics other hydrocartion comprises treatment orhydrocarioon boils p i some para-fins of branched tures w i normally liquid it. amichain structure and the usual run of naphthenes cyclic compounds with catalysts comprising and aromatics. The isomerization of individual ides of the Friedel-Craits type and hydrogen haln-hexane is frequently desirable in the manufacuid paramns. ture of derivates since the isomeric compounds We have found that the results obtained when or gasoline fractions, the isomerization has the gasoline range cont 1: parafimc hydrocareffect of increasing the antilmock value of the 2 bone and the usual run of cyclic hydrocarbons sasolines to a marked extent as will be shown suchas naphthenes and aromatics are considerln later exples. ahlyimproved over those obtained when tree There should be no need for extensively rethe para hydrocarbons in the absence of these counting the number of possible isomer iof parcyclic hydrocafioons. 1 aihn hydrocarbons since these are all predictable 0. In the isomerization of normally liquid parai on the present theories of organic chemistry and fin hydrocarbons by contact with halide catalysts are well known to those familiar with this suhof the Friedel-Craits type in the presence of a ject. However, the following table isshown to hydrogen halide under isomerizins conditions of indicate in a general way the change in structemperature and pressure, considerable decobons and their isomers, particularlylsince the neously with the isomerization reaction. The pentanes cotute some of the lower-boiling v fraemental hydrocarbons formed during the deconstituents oi ordinary gasolines. composition unite with the halides or the Friedel= Compound I Formula z i g I. Density] g m.

I v c. v

n-Pentane..... onnonoiom sea 0.c475@c0 es A on j Itoam..- onomommm; n monsoon... so

x Ofi Nee-Penman own, y 9.5 0.6251@14.4 o I It will be from the shove that; as the form complexes co only called structure oi the molecule becomes more com sludgeformation of sin e e I pact. ho i at; point and specific gravity both dea considerable at the cata consumption crease, while th och value as expressed by per unit weight of i m by hon increases although fiserized and inucee my one sdimculties' in the process such as separation and disposal of the sludge. If, however, straight run gasoline fractions containing the usual percentages oi paraflins and cycliccompounds such as aromatics are isomerized under similanconditions, the amount of decomposition and other side-reactions is considerably decreased. Particularly suitable stocks for treatment in the process of the present invention are straight run gasoline fractions, for example, the hexane fraction obtained from straight run gasolines such as Michigan or Mid-Continent gasolines, containing aromatic hydrocarbons usually consisting of henzone in percentages of the order of 0.3 to about- 2%. Aromatic hydrocarbons such as benzene and toluene which are ordinarily present in fractions of straight run gasoline are particularly effective in inhibiting decomposition reaction during the isomerization process.

.There are several alternative catalysts which? may be employed in accomplishing the isomerization reaction among the paraflin hydrocarbons.

While they may be used more or less interchangeably, some argmore efiective thanthe others and lt is not intended to infer that they are definitely equivalent. Among the compounds ,which may.

be employed are the halides oi the Friedel-Crafts type such as aluminum halides, zirconium halides, zinc halides, iron halides, boron fluoride, either 'alone or in admixture with one another, or in admixture with compounds such as antimony,

arsenic and bismuth compounds which form lowmelting catalyst mixtures. Suitable catalysts may be also derived by the reaction of these halides with hydrocarbons to form catalytically active complexes. The solid catalysts may be used in a granular state or deposited upon supporting materials'such as alumina, bauxite, activated clays, activated carbon, and other wellknown supporting agents. Extensive experiments have indicated that best results are obtained when a hydrogen halide is present in the reaction zone along with these compounds. There will be some variations in relative amounts of Friedel-Crafts type compounds and hydrogen halides used at.

optimum treating conditions but the determination of these ratios is somewhat a matter of experiment. The combination of aluminum chlo-' ride and hydrogen chloride is usually preferable over the other possible combinations. Ordinarily when utilizing this particular combination, a hychosen and the hydrocarbon mixture undergoing treatment. A simple method of operation-consists in adding 5 to 10 percent of granular anhydrous aluminum chloride to a treating vessel containing hydrocarbons and provided with a mechanical agitating device of some description. It is best to employ a treater which can be sealed from atmospheric contact and which can be operated under' pressure it necessary. The solid catalyst is then 'kept in suspension by moderate agitation while introducing a slow stream-oi hygranular catalysts comprising the preferred metal halides, anexample of such catalysts being the composite produced by impregnating the pores of activated carbons with sublimed aluminum chloride.

-In the case of, readily vaporizable metallic halides such as aluminum chloride, it may be sublimed directly into a stream of hydrocarbon vapors and the hydrogen chloride'iollowed by settling of spent catalyst and fractionation of the products. r 1 The following examples are introduced to examplify the improved results obtained in the operation of the process, but they are not given with a the intention or limiting the scope of the invendrogen chloride concentration is usually below approximately 40 molpercent oi" the charge.

The specific conditions of temperature, pressure and hydrogen halide concentration are dependent primarily upon the particular hydrocarbon mixture and catalyst used in the isomerization reaction. However, in the broad aspects of "the invention, the temperature will vary from.

10 to about 250 C. When a specific hydrocarbon fraction such as a hexane fraction obtained from a straight run gasoline and containing the usual amount or cyclic hydrocarbonsv such as an aromatic content of about 0.5 to 1.5% is-contacted with aluminum chloride in the presence oi. hydrogen chloride, the desired operating temperature for said results will ordinarily be within the range oi. 10 to about 200 C. When various other catalysts such as zinc chloride and zirconium chloride are utilized; temperatures in the neighborhood of 250 C. maybe used.

The processqmay be operated under batch or continuous conditions and either in liquid, mixed or vapor-phase as may be desirable or expedient tion in exact correspondence with the numerical data presented.

' Example I In this example, the gasoline fraction boiling within the range of to 90 C. obtained-from a highly paramnic Michigan gasoline was treated. The fraction had an octane number of 54 and corresponded'roughly to a mixture of hexanes and cyclic compounds such as cyclohexaneand.

benzene. This fraction was-subjected to isomerization tor the improvement or its antiknock value. in the presence of aluminum chloride and hydrogen chloride at two temperatures to observe the effect at each. The gasoline fraction was The octane number or the product wascon'siderplaced in a pressure vessel, aluminum chloride was added, and the heating was conducted over a period of 6 hours after which the vessel was cooled and gaseous liquid hydrocarbons recovered and examined. The following table gives the principal results obtained in the two runs.

Run #1 Run #2 'lemperature g 0. me

Charge-in treater "gasoline," pts. by wt 200. 0 200. 0 AlCh, p 20. 0 20. 0 H01, pts by wt. (approximate 15 6 a 16 45 Octane No. oiproduct 72 Liquid product per cent by wt. oi chg 87 i 75.3

ably improved over that of the charge with only moderate losses'oi char e due to gasformation and minor amounts or aluminum chloride-hydro in'view of the particular catalyst combination to ca'i'boii complexes.

value and non-olefinic cyclic hydrocarbons to the.

Example 11 A pentane fraction containing about 0.5 volume percent benzene was contacted with aluminum chloride in the presence of mol percent of hydrogen chloride. The temperature and pressure in the reaction zone was 100 C. and.- 500 pounds per square inch gauge. A once through yield of about 52 volume percent oi isopentane was produced per pass with substantially no production of light gases or hydrocarbons boiling higher than normal pentane. A'substanl tial portion of the benzene was recovered in the product.

' In a second experiment in which normal pentane free of benzene was contacted with aluminum chloride and hydrogen chloride under the same conditions, a once through yield of about 29 volume percent isopentane was obtained. However, about 30 volume percent of the normal pentane was converted to isobutane and hydrocarbon boiling higher than normal pentane.

In comparing the results of the two experiments given above, it is evident that the presence of the aromatic-hydrocarbon, namely benzene, inhibited the decomposition of the normal pentane to higher and lower boiling hydrocarbons. It is apparent that on a recycle basis, the advantage obtained by the addition of benzene would be considerably more prominent in that the efficiency of the isomerization operation in which benzene is present is about 97% while in the second experiment where pentane alone is isomer- I ized, the efiiciency is below about 50%.

We claim as our invention:

1. A process for isomerizing a normally liquid parafiln hydrocarbon boiling in the gasoline range which comprises subjecting'said paraffin, while in admixture with a non-olefinic cyclic hydrocarbon, to the action of an isomerizing catalyst of the Friedel-Crafts type in the presence of added hydrogen halide and under isomerizing conditions of temperature, pressure and time, and correlating the amount of hydrogen halide and said isomerizing conditions of temperature, pressure and time to convert a substantial portion of said paraffin into an isomer or isomers thereof having the same molecular weight as said paraffin.

2. A process for isomerizing a normally liquid parafiin hydrocarbon boiling in the gasoline range which comprises subjecting said paraflin, while in admixture with a non-olefinic cyclic hydrocarbon, to the action of an aluminum halide in the presence of added hydrogen halide and under isomerizing conditions of temperature, pressure and time, and correlating the amount of hydrogen halide and said isomerizing conditions of temperature, pressure and time to convert a substantial portion of said paraflin into an isomer or isomers thereof having the same molecular weight as said paraffln.

3. A process for increasing the anti-knock properties of gasoline boiling para fiins which comprises subjecting a normally liquid hydrocarbon fraction boiling in the gasoline range and containing parafiins of relatively low anti-knock action of an isomerizing catalyst oi the Friedel- Crafts type in the presence of an added hydrogen halide under isomerizing conditions of temperature, pressure and time, and correlating the amount of hydrogen halide and said isomerizing conditions of temperature, pressure and time to convert a substantial portion of the parafiins contained in said fraction into isomers thereof having the same molecular weight as and of higher anti-knock properties than said paraifins.

4. The process as defined in claim 3 further characterized in that said isomerizing'catalyst comprises an aluminum halide.

5. The process as defined in claim 3 further characterized in thatsaid isomerizing catalyst comprises aluminum chloride and. in that said hydrogen halide is hydrogen chloride.

6. The process as defined-in claim 1 further characterized in that said isomerizing catalyst comprises an aluminum halide and-in that said paraffin contains less than 7 carbon atoms.

7. The process as defined in claim 1 further characterized in that said isomerizing catalyst comprises aluminum chloride and in that said hydrogen halide is hydrogen chloride.

8. The process as defined in claim 1 further characterized in that said cyclic hydrocarbon is a naphthene.

9. The process as defined in claim 2 further characterized in that said cyclic hydrocarbon is anaphthene.

10. The process as defined in claim 3 further 5 characterized in' that said cyclic hydrocarbons comprise a naphthene.

11. A process for increasing the anti-knock properties of gasoline boiling paraflins which comprises subjecting a normally liquid hydrocarbon fraction boiling in the gasoline range and containing parafiins of relatively low anti-knock value and a naphthene to the action of an aluminum halide in the presence of an added hydrogen halide under isomerizing conditions of temperature, pressure and time, and correlating the amount of hydrogen halide and said isomerizing conditions of temperature, pressure and time to convert a substantial portion of the paraifins contained in said fraction into isomers thereof having the same molecular weight as and of higher anti-knock properties than said paraffins.

12. A process for isomerizing a normally liquid parafiin hydrocarbon boiling in the gasoline range which comprises subjecting said parafiin, while in admixture with a naphthene, to the action of aluminum chloride in the presence of added hy. drogen chloride andunder isomerizing conditions of temperature, pressure and time, and correlating the amount of hydrogen chloride and said isomerizing conditions of temperature, pressure and time to convert a substantial portion of said paraflin into an isomer or isomers thereof having the same molecular weight as said parafiin.

.ARIS'I'ID V. GROSSE. HERMAN PINES. 

